Since compartment-per-global landed (bug 650353), some of our Mozmill tests have started to perma-orange with an error stating that:
Test Failure: controller(): Window could not be initialized.
The Mozmill devs themselves got broken by 650353 (see 751424), and they're rapidly working to fix themselves up.
When their patch lands, we'll have to modify our workaround (bug 666438) in _wait_for_generic_load in test-window-helpers.js, but then we should be back in business. I just tried an early version of the Mozmill patch with a variation on our workaround with positive results.

Created attachment 621449[details][diff][review]
Fix _wait_for_generic_load to use Mozmill's new controller.windowMap
Henrik says that the Mozmill team is planning on landing their CPG fix in Mozmill 1.5.12 soon, so we're going to have to upgrade.
We'll also need to change our approach to the window workaround we were doing before. This patch, combined with an early draft of Henrik's work, had good results in test-fixage.